As a material efficiently absorbing infrared light or visible light in a broadband, black silicon using a blackened film using metal nanoparticles or carbon-based materials or black silicon using an array of needle-like silicon (PTL 1) is known in the conventional art. Light absorption in broadband over visible and infrared regions can be performed by using the elements described above. Meanwhile, a three-dimensional vertical microcavity structure or a line-and-space type resonator structure which performs treatment with respect to surfaces of precious metals or high-melting-point metals such as gold, tungsten, or nickel to cause confinement of surface plasmon in a surface vertical direction has been studied as a material exhibiting electromagnetic wave absorption in a narrowband, and visible-infrared light-absorbing materials having absorption properties in a narrowband have been developed (NPL 1). It is found that these materials can also be used as a light source of visible light or infrared light in a narrowband by being heated and the light source is operated as a visible light source or an infrared source capable of adjusting a radiation wavelength, by selecting dimensions of a cavity structure.
However, since the cavity structure of these is a three-dimensional structure, it is necessary to perform top-down processing methods causing a high cost such as focused ion beam processing, electron beam lithography, and nanoimprint methods for manufacturing the structure. When a step of performing vapor deposition with respect to metals using sputter deposition, vacuum deposition or the like is used, there are restrictions so that manufacturing accuracies of a depth direction and a transverse direction or a surface shape of a cavity structure are not obtained. In addition, even when a wall surface orthogonal to the surface is intended to be formed when forming holes or grooves, an unintended tapered inclination may be generated, in many cases. Such a problem causes a problem of not achieving properties of absorbing and radiating efficiency as design. In addition, since the processing methods described above may be not suitable for large area processing, there are also restrictions in applicable fields of these type of materials manufactured using the conventional art. As described above, it is required to simplify a complicated manufacturing step, decrease a cost thereof, and improve manufacturing accuracies and properties.
Further, tungsten, gold, or nickel, which are precious metals or heavy metals, causes a high cost and a great weight. Therefore, it is also required to provide a material having a new structure capable of being manufactured even when light and inexpensive materials having high suitability for mass production which can be easily manufactured as a product are used.
It is possible to manufacture a material which efficiently absorbs light and electromagnetic waves at a wavelength close to a specific wavelength using a precious metal-dielectric-precious metal laminated type metamaterial structure. Such electromagnetic wave-absorbing material can be applied for realizing high efficiency of a high-sensitive hydrogen sensor, a carbon dioxide sensor, or a solar cell. However, in the conventional art, only materials obtained by using a lithography process with a focused ion beam or an electron beam, or nanoimprinting which is a process which causes high cost and takes a long time, using precious metals such as gold or silver, have been realized (NPLs 2 to 5).
In addition, since metals having a comparatively low melting point such as gold, silver, or aluminum were used in electromagnetic wave absorbing/radiating materials of the conventional art, the materials have poor heat resistance and did not withstand the usage at a high temperature. According to Planck's law, as a temperature of an object increases, an intensity of heat radiation increases. Accordingly, particularly, in a case of aiming at providing a radiating material, it is necessary to heat the material to a higher temperature, in order to obtain a greater radiation intensity, and thus, it is required to obtain higher heat resistance.